Human beings are probably inherently religious.1 It is impossible to live without an implicit value system. To live is to make thousands of little choices every day about what and what not to think about, what and what not to do, how and how not to allocate one’s limited time, attention, and resources.
It is possible to care about nothing but one’s own aggrandizement, to pursue only the false gods of pleasure, wealth, status, and power. It is possible to live without, or almost wholly without, belief in or sustained contact with anything outside the material plane.
But in all times and places, many, or most, people will discover that such a lifestyle and worldview are unsatisfying. They may experience suffering and find their worldview inadequate in its face. They may get all they think they want, only to find themselves feeling empty.
In response, they will seek ways to transcend egotism and materiality, to confer meaning on, and find consolation in, suffering. “I used to think the opposite of spiritual was material,” Michael Pollan has said, “and I realize that’s not really right. The opposite of spiritual is egotistical.”
One way to think about God is that God is the only appropriate, or psychologically satisfactory, object of worship:
You made us for yourself, and our heart is restless until it rests in thee.
If we find ourselves with a desire that nothing in this world can satisfy, the most probable explanation is that we were made for another world.
Assuming nihilism is possible, not all individuals have beliefs and rituals that offer meaning, transcendence, and consolation. But all societies do. For the reasons given, it could not be otherwise.
Yet, only some of these belief-ritual complexes merit the name religion. Unlike most secular ideologies, religions have deep, organic histories and develop through a kind of Darwinian process.
Take Catholicism. The Catholic Church has existed for many hundreds of years, in tens of thousands of localities, scores of countries and empires, and every continent. It is an institution that has served and shepherded hundreds of millions of individuals through every stage of life, through the most sublime joys and profound griefs and disillusionments.
Its central texts, values, rituals, and artistic works are central, in part, because they have been found useful and valuable across time and space – in a way no rationally constructed system could. These elements reflect incalculable trial and error and constitute a vast repository of passionate, considered response to human life in its manifold variety.
Of organic necessity, the Church takes into consideration the entire community, not part of it; it tells the whole moral story, not half of it; it produces timeless art, not kitsch; it locates transgression in every individual, not in some groups as against others; and crucially, it imposes private duties on its adherents, which, running counter to instinct, are hard to observe but conducive to individual and collective fulfillment.
Have you read Chateaubriand's _The Genius of Christianity_? If not, highly recommended.